CN110596651A - Radar detection method - Google Patents

Radar detection method Download PDF

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Publication number
CN110596651A
CN110596651A CN201910841551.3A CN201910841551A CN110596651A CN 110596651 A CN110596651 A CN 110596651A CN 201910841551 A CN201910841551 A CN 201910841551A CN 110596651 A CN110596651 A CN 110596651A
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signal
signals
target
detection
sum
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CN201910841551.3A
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CN110596651B (en
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唐剑聪
金胜
邓振淼
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Guangzhou Tianyan perception Technology Co.,Ltd.
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Xiamen University
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
    • G01S13/02—Systems using reflection of radio waves, e.g. primary radar systems; Analogous systems
    • G01S13/04—Systems determining presence of a target
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
    • G01S7/28—Details of pulse systems
    • G01S7/285—Receivers
    • G01S7/292—Extracting wanted echo-signals
    • G01S7/2923—Extracting wanted echo-signals based on data belonging to a number of consecutive radar periods
    • G01S7/2927—Extracting wanted echo-signals based on data belonging to a number of consecutive radar periods by deriving and controlling a threshold value
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
    • G01S7/28—Details of pulse systems
    • G01S7/285—Receivers
    • G01S7/292—Extracting wanted echo-signals
    • G01S7/2923—Extracting wanted echo-signals based on data belonging to a number of consecutive radar periods
    • G01S7/2928—Random or non-synchronous interference pulse cancellers

Abstract

The invention relates to a radar detection method, wherein a radar transmits a linear frequency modulation signal, and an antenna receives the linear frequency modulation signal after the linear frequency modulation signal is reflected by a target to obtain an echo signal. When the number of received signal echoes reaches the number N of resident pulses, performing matched filtering and two-dimensional inverse Fourier transform on the echo signals of N times to obtain two-dimensional time domain signals, and squaring the two-dimensional time domain signals to obtain square filtering signals; and performing CFAR detection on the square filtering signal, calculating the average power of the background noise, and finally comparing the average power of the background noise with the square filtering signal to detect the target signal. According to the invention, four areas outside the cross window, the protection unit and the detection unit are selected as reference units, so that the average background noise power of each unit to be detected is calculated more accurately, and the accuracy of target detection is improved.

Description

Radar detection method
Technical Field
The invention relates to the technical field of radars, in particular to a radar detection method.
Background
Before the radar measures the distance and speed of the target, whether the target exists or not must be detected, and the detection of the target is an important component of target positioning.
Conventional one-dimensional CFAR (Constant False Alarm Rate) detection forms a leading edge and trailing edge local estimate using an average of reference samples in leading edge and trailing edge reference units, and then averages or selects the size or weights the two local estimates to determine a background clutter average power level estimate for the detection unit. The two-dimensional CFAR is based on the one-dimensional CFAR, the detection of the velocity dimension is added, so that the cross window CFAR detection is formed, and whether a target is detected or not can be confirmed by comparing the unit to be detected with the estimated background noise power.
The conventional two-dimensional CFAR cross-window detection mainly has two disadvantages: firstly, a cross window dimension reference unit is used, and only a few reference units are used for estimating the average power of background noise, so that the estimated background clutter power is inaccurate; secondly, when multiple targets are generated and the targets are close to each other, due to the adoption of cross window detection, a target value with a larger amplitude and a smaller shielding amplitude may be generated, so that the small target may not be detected, and the target detection omission phenomenon is caused.
In view of the above, the present invention is conceived based on the problems in the field of radar detection, and is further developed.
Disclosure of Invention
The invention aims to provide a radar detection method which can accurately calculate the average power of background noise of a unit to be detected and improve the accuracy of target detection.
In order to achieve the purpose, the invention adopts the technical scheme that:
a method of radar detection, comprising the steps of:
step 1, a radar transmits a linear frequency modulation signal s (t), after the signal is reflected by a target, an antenna receives an echo signal, and the echo signal is r (t);
step 2, when the number of the echoes received by the antenna is equal to the number of the resident pulses N, matching filtering is carried out on the echo signals R (t) received by the antenna each time by taking the transmitted linear frequency modulation signals s (t) as reference signals to obtain matched filtering frequency domain signals R each timem(f) (f) s (f), wherein R (f) and s (f) are the fourier transforms of R (t) and s (t), respectively, and the two-dimensional frequency domain discrete signal R is recordedN,K(N, k) are the matched filtering results of the N echo signals;
step 3,For two-dimensional frequency domain discrete signal RN,K(n, k) performing two-dimensional inverse Fourier transform to obtain a two-dimensional time domain signal rN,K(n, k) squared to obtain a squared filtered signal
Step 4, adopting a cross window to square the filtering signalProcessing to form a unit to be detected and a protection unit, taking four regions except the cross window, the detection unit and the protection unit as background reference units, and clockwise recording the sum of the regions from the upper left corner to sum1、sum2、sum3、sum4Selecting the second and third phases in the sequence and multiplying the sum by the detection factor to calculate the average power of the background noise
Step 5, square-law wave signals generated in the step 3 and the step 4 are subjected toAnd background noise average powerAnd each point is correspondingly compared, if the former is larger than the latter, the target exists, otherwise, the target does not exist.
After the scheme is adopted, the echo signals of the N pulses are respectively subjected to matched filtering processing, so that the influence of noise on the signals is reduced, and the signal-to-noise ratio is improved. Meanwhile, four areas outside the cross window, the protection unit and the detection unit are selected as reference units, so that the average background noise power of each unit to be detected is calculated more accurately, and the accuracy of target detection is improved.
Drawings
FIG. 1 is a flow chart of the present invention;
FIG. 2 is a schematic diagram of two-dimensional CFAR detection according to the present invention;
fig. 3 is a diagram illustrating a target detection result according to an embodiment of the present invention.
Detailed Description
As shown in fig. 1, the present invention discloses a radar detection method, which comprises the following steps:
step 1, the radar transmits a linear frequency modulation signal s (t), after the signal is reflected by a target, an antenna receives an echo signal, and the obtained echo signal is r (t).
Step 2, when the number of the echoes received by the antenna is equal to the number of the resident pulses N, matching filtering is carried out on the echo signals R (t) received by the antenna each time by taking the transmitted linear frequency modulation signals s (t) as reference signals to obtain matched filtering frequency domain signals R each timem(f) (f) s (f), wherein R (f) and s (f) are the fourier transforms of R (t) and s (t), respectively, and the two-dimensional frequency domain discrete signal R is recordedN,KAnd (N, k) is the matched filtering result of the N echo signals.
Step 3, carrying out two-dimensional frequency domain discrete signal RN,K(n, k) performing two-dimensional inverse Fourier transform to obtain a two-dimensional time domain signal rN,K(n, k) squared to obtain a squared filtered signal
Step 4, the obtained square filtering signal is subjected toUsing the two-dimensional CFAR detection method of the present invention, as shown in FIG. 2, a cross-window is used to square the filtered signalProcessing to form a unit to be detected and a protection unit, simultaneously taking four regions except the cross window, the detection unit and the protection unit as background reference units, clockwise recording the sum values of the regions as sum1, sum2, sum3 and sum4 from the upper left corner, selecting the second phase and the third phase which are sequenced, adding and multiplying the detection factors, and calculating to obtain the unit to be detected and the protection unitAverage power of background noiseWherein the detection factor is defined as:wherein p isfaThe false alarm probability is shown, and n is the number of reference units; and calculating the average power of the background noise of each unit in turn.
Step 5, square-law wave signals generated in the step 3 and the step 4 are subjected toAnd background noise average powerAnd comparing, wherein if the former is larger than the latter, the target exists, otherwise, the target does not exist.
To elaborate the technical scheme of the invention, an embodiment will be illustrated below.
Suppose there are 3 objects whose three-dimensional positions in space are r1＝[1400,1000,500]，r2＝[1280,880,494]，r3＝[1160,760,488]The unit m; three-dimensional velocities are respectively v1＝[-1000,-1000,-1500]，v2＝[-1060,-1060,-1560]，v2＝[-1120,-1120,-1620]In m/s; the target three-dimensional acceleration is respectively: a is1＝[0,0,0]，a2＝[-6,-6,-6]，a3＝[-12,-12,-12]Unit m/s2(ii) a The radar carrier frequency is 10GHz, the pulse width is 4us, the sampling frequency is 320MHz, and the number of resident pulses N is 200.
The detection method is adopted to detect 3 targets, and the obtained detection result is shown in fig. 3.
The key of the invention is that the invention adopts the matched filtering processing to the echo signals of N pulses respectively to reduce the influence of noise on the signals and improve the signal-to-noise ratio. The CFAR two-dimensional detection is adopted, namely four areas outside the cross window, the protection unit and the detection unit are selected as reference units, and the background noise reference units are fully utilized, so that the average background noise power of each unit to be detected is calculated more accurately, and the accuracy of target detection is improved.
The above description is only exemplary of the present invention and is not intended to limit the technical scope of the present invention, so that any minor modifications, equivalent changes and modifications made to the above exemplary embodiments according to the technical spirit of the present invention are within the technical scope of the present invention.

Claims (1)

1. A method of radar detection, characterized by: the method comprises the following steps:
step 1, a radar transmits a linear frequency modulation signal s (t), after the signal is reflected by a target, an antenna receives an echo signal, and the echo signal is r (t);
step 2, when the number of the echoes received by the antenna is equal to the number of the resident pulses N, matching filtering is carried out on the echo signals R (t) received by the antenna each time by taking the transmitted linear frequency modulation signals s (t) as reference signals to obtain matched filtering frequency domain signals R each timem(f) (f) s (f), wherein R (f) and s (f) are the fourier transforms of R (t) and s (t), respectively, and the two-dimensional frequency domain discrete signal R is recordedN,K(N, k) are the matched filtering results of the N echo signals;
step 3, carrying out two-dimensional frequency domain discrete signal RN,K(n, k) performing two-dimensional inverse Fourier transform to obtain a two-dimensional time domain signal rN,K(n, k) squared to obtain a squared filtered signal
Step 4, adopting a cross window to square the filtering signalProcessing to form a unit to be detected and a protection unit, taking four regions except the cross window, the detection unit and the protection unit as background reference units, and clockwise recording the sum of the regions from the upper left corner to sum1、sum2、sum3、sum4Selecting the second and third phases in the sequence and multiplying the sum by the detection factor to calculate the average power of the background noise
Step 5, square-law wave signals generated in the step 3 and the step 4 are subjected toAnd background noise average powerAnd each point is correspondingly compared, if the former is larger than the latter, the target exists, otherwise, the target does not exist.
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CN111398922A (en) * 2020-04-27 2020-07-10 厦门大学 Improved CFAR detection method

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CN111398922A (en) * 2020-04-27 2020-07-10 厦门大学 Improved CFAR detection method

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